Pinpoint Test L: The Brake Warning Indicator Is Never On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test L: The Brake Warning Indicator Is Never On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 13, Power Distribution/SJB for schematic and connector information. Diagrams By Number
Normal Operation
The brake warning indicator alerts the driver if any of the following brake system conditions are present: the parking brake is set, the brake fluid level is low, the ABS module detects a base brake system failure, there is a loss of communication between the Instrument Cluster (IC) and the Smart Junction Box (SJB), or there is a loss of communication between the IC and the ABS module.
When the parking brake is applied, circuit 1309 (RD/YE) to the SJB is grounded by the parking brake switch through circuit 1205 (BK). The SJB receives the ground signal and sends the IC a message over the communication network to illuminate the brake warning indicator. When the brake fluid level is low, the brake fluid level switch closes, providing a signal to the SJB on circuit 547 (LG/YE) which is then routed back to the SJB on the signal return circuit 512 (TN/LG). When a base brake system concern is detected, the ABS module sends a signal to the IC over the communication network to illuminate the brake system warning indicator.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Parking brake switch
- Brake fluid level switch
- SJB
- IC
PINPOINT TEST L: THE BRAKE WARNING INDICATOR IS NEVER ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
-------------------------------------------------
L1 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC brake warning indicator (BRK_LAMP) active command on while monitoring the brake warning indicator.
- Does the brake warning indicator illuminate?
Yes
GO to L2.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
-------------------------------------------------
L2 CHECK THE BRAKE WARNING INDICATOR WITH THE PARKING BRAKE APPLIED
- Apply the parking brake while monitoring the brake warning indicator.
- Does the brake warning indicator illuminate?
Yes
GO to L7.
No
GO to L3.
-------------------------------------------------
L3 CHECK THE PARKING BRAKE SWITCH PID
- Apply the parking brake.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB parking brake switch PID (PRK_BRK) while applying the parking brake.
- Does the PID agree with the parking brake position?
Yes
GO to L10.
No
GO to L4.
-------------------------------------------------
L4 CHECK THE PARKING BRAKE SWITCH
- Ignition OFF.
- Disconnect: Parking Brake Switch C306.
- Connect a fused jumper wire between the parking brake switch C306-1, circuit 1309 (RD/YE), harness side and the parking brake switch C306-2, circuit 1205 (BK), harness side.
- Ignition ON.
- Does the brake warning indicator illuminate?
Yes
REMOVE the jumper wire. INSTALL a new parking brake switch. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to L5.
-------------------------------------------------
L5 CHECK CIRCUIT 1205 (BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the parking brake switch C306-2, circuit 1205 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to L6.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
L6 CHECK CIRCUIT 1309 (RD/YE) FOR AN OPEN
- Disconnect: SJB C2280c.
- Measure the resistance between the SJB C2280c-50, circuit 1309 (RD/YE), harness side and the parking brake switch C306-1, circuit 1309 (RD/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L10.
No
REPAIR the circuit. TEST the system for normal operation.
-------------------------------------------------
L7 CHECK THE SJB OPERATION USING THE SCAN TOOL
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Connect a fused jumper wire between the brake fluid level switch C124-2, circuit 547 (LG/YE), harness side and the brake fluid level switch C124-1, circuit 512 (TN/LG), harness side.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB brake fluid level PID (BRK_FLUID).
- Does the PID indicate low brake fluid level?
Yes
REMOVE the jumper wire. INSTALL a new brake fluid level switch. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to L8.
-------------------------------------------------
L8 CHECK CIRCUIT 512 (TN/LG) FOR AN OPEN
- Ignition OFF.
- Disconnect: SJB C2280c.
- Measure the resistance between the SJB C2280c-35, circuit 512 (TN/LG), harness side and the brake fluid level switch C124-1, circuit 512 (TN/LG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L9.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
L9 CHECK CIRCUIT 547 (LG/YE) FOR AN OPEN
- Measure the resistance between the SJB C2280c-48, circuit 547 (LG/YE), harness side and the brake fluid level switch C124-2, circuit 547 (LG/YE), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to L10.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
L10 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify that the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------